I'm reading reports of guys putting a 1.4X TC on their 400/5.6 lenses. That lens has super quick AF with most bodies. They're reporting that it only loses a little speed at f/8 now. For under $2000 you can have a really effective 540mm.

Dave

I've got the 300f4L IS and at one point had the vers. I 1.4x TC on the crop body, but let it go to a friend as they were just releasing the vers III and I figured I'd upgrade.. then forgot as I dont shoot long all that often. BUT now that I'm watching all this great action and reading up more on compression.. You've got me thinking I should pair that new firmware and my 5d3 with a 2.0X TC and my 300! 600mm would be great and I could also snap it on to the 70-200 if I wanted something in between. Thoughts?